The invention relates to a valve block for use with an I.S. machine for forming hollow glass articles. This type of machine forms the glass articles by first press or blow molding a gob of molten glass into a parison or blank of molten glass. The formed blank or parison is then transferred to a blow mold wherein it is subjected to a blowing process for forming the hollow glass article into its final shape.
The various functions of the forming machine are all pneumatically actuated. Some of the functions to be performed include: actuating a plunger during the press and blow operation, actuating cylinders for controlling mold and blank arms, inverting the parison, moving the funnel, baffle and scoop, etc. A valve block is interposed between a source of pressurized air and the forming machine. The valve block performs the function of supplying pressurized air to the various stages of the forming machine in a properly timed sequence. A prior art valve block is disclosed in U.S. Pat. No. 3,918,489.
The valve block itself has a plurality of valve stations which each in turn supplies air for a specific function of the forming machine. Each of the valve stations is connected to a source of pressurized air. Each of the valve stations has a cartridge or supply valve which has a valve member biased to a closed position in order to block communication from the source of air until its associated function is to be performed. When a valve's associated function is to be performed, the valve member is moved to a position which permits the pressurized air to flow through the valve station into the forming machine. The timing of the actuation of such supply valves can be accomplished either mechanically or electronically. In the preferred embodiment of the present invention, supply valves are electronically controlled.
A major drawback of the valve blocks of the prior art is the difficulty of the maintenance of the valves within the block. In order to change or service a valve within a prior art block, a major portion of the valve block assembly has to be removed. Such an operation takes approximately one hour. Another drawback of the prior art valve blocks is the excessive noise generated by such blocks.
A further disadvantage of the prior art valve blocks is the limited speed with which the blocks could supply air to a forming machine. The speed with which the functions of the forming machine could be performed was thereby also limited. Prior art devices attempted to overcome this limitation by supplying the air at higher pressures. This solution proved unsatisfactory in that it led to excessive and quick wear upon the valve blocks and machine.